I. Field of the Invention
The present invention relates to insulation for use in buildings, houses, vehicles, boxes and the like, and more specifically to reflective insulation.
II. Background Art
Reflective insulation employs thin sheets which have heat reflective metal surfaces in conjunction with air spaces adjacent to them to provide reflective insulation, with the resulting structure being very effective against radiative heat transmission, as well as conduction and convection. Insulation of this type is low cost with regard to the materials required, which are usually merely aluminum foil and paper. It is also economical for shipping, packaging, storage and handling because it is collapsible, folding into a flat, stackable unit.
Constant spacing between the sheets of paper and foil are critical to the effectiveness of the reflective insulation. Because the foil is conductive, it must not be allowed to touch any other conductive surface, thus the reason for the alternating layers of paper and foil. In addition, it is also important that the air space itself between the paper and foil be kept constant. The most common method of maintaining the spacing between the sheets is to stretch the insulation between two beams, attaching the ends with a fastener such as a nail or staple, with the idea of holding the sheets under tension longitudinally so they remain parallel. If the sheets are maintained under excessive tension, however, their lifetime may be shortened because the sheets may tear or collapse after being subjected to repeated shock or vibration. Attempts to support the spaces by insertion of intermediate foundation layers which divide the air spaces into triangular sections, as in U.S. Pat. No. 2,786,004 of Schwartz, et al., decreases the insulating value of the reflective air space.
One of the greatest drawbacks of reflective insulation is that methods of fastening the insulation to the structure place the ends of the insulation under forces which at least partially compress the spaces adjacent to the supporting edge, resulting in weak thermal resistance at that point. Unfortunately, all currently available reflective insulation requires attachment of the supporting edge to the beams of a construction bay, the construction bay being the space between studs, beams, rafters, purlins, etc. in the structure being insulated.
Another drawback is that when buildings are used as storage facilities the insulation is often left unprotected from the inside, exposing the fragile sheets of foil and paper to damage due to inadvertent contact with objects in the building.
It would be desirable to provide a reflective insulation unit which is collapsible for ease in transportation and storage and which, when installed, provides continuously extending sheets which remain parallel and are maintained taut over the entire width of the insulation unit in proper spaced relationship without relying on attachment to the beams of the structure being insulated. It is also desirable to provide a protective housing for the reflective insulation to enhance its lifetime and effectiveness and not requiring the open ends to be butted against purlins, studs, or trusses in order for the product to perform.